Vinegar will COMPLETELY disolve brass if left submerged in enough of it for a long enough time. (Don't ask how I know that.)

So, you need to monitor the brass to see when it is sufficiently de-stained for your liking, rather than just leave it to soak until you get around to looking at it again. You CAN damage/weaken brass to the point where you should not shoot it, IF you don't pay attention.

But, vinegar is not such a strong acid that the soak time needs to be TIGHTLY controlled, as with some of the OLD military methods.